A power amplification circuit in a wireless system is typically a large signal device. In wireless local area network (WLAN) systems, the power amplifier (PA) circuit may transmit output signals at average power levels in the range of 10 dBm to 20 dBm, and peak power levels of about 20 to 30 dBm, for example. In such WLAN systems, which may, for example, utilize a wide range of modulation types from binary phase shift keying (BPSK) to 512 level quadrature amplitude modulation (512-QAM), output power levels may vary widely such that the ratio of the peak power level to the average power level may be large, for example, 10 dBm to 15 dBm.
The power output of a PA can be affected by the voltage level measured by a level detector. An inaccuracy in the level detector may cause the system to be designed with decreased output power of the PA, such that the FCC or standard's limit is never exceeded. If the uncertainty in the measured output power is 4 dB, for example, then the output power of the PA may have to be reduced by 4 dB below the FCC limit so as to never exceed that limit, greatly reducing the range of the transmitter
Limitations in the performance of PA circuitry may be exacerbated when the PA is integrated in a single integrated circuit (IC) device with other radio frequency (RF) transmitter circuitry [such as digital to analog converters (DAC), low pass filters (LPF), mixers, and RF programmable gain amplifiers (RFPGA)]. Whereas the pressing need to increase the integration of functions performed within a single IC, and attendant increase in the number of semiconductor devices, may push semiconductor fabrication technologies toward increasingly shrinking semiconductor device geometries, these very semiconductor fabrication technologies may impose limitations on the performance of the integrated PA circuitry. For example, utilizing a 65 nm CMOS process may restrict the range of input power levels for which the PA provides linear output power level amplification.
Further limitations and disadvantages of conventional and traditional approaches will become apparent to one of skill in the art, through comparison of such systems with the present invention as set forth in the remainder of the present application with reference to the drawings.